A tracking device is intended to facilitate finding an object to which it is attached by sending tracking messages. These messages by definition are tracking messages on the basis of their origin, even if they are being forwarded by a data processing device, possibly after translation by the data processing device for a different transmission technology.
Known tracking devices which use short-range radio technology enable a mobile data processing device, for example a mobile telephone, to check its connection with them often. An alarm is generated if an object with a tracking device is being distanced from the mobile telephone in other words, if a durable connection to the attending mobile telephone is lost. These tracking devices do not require a motion detector. In most cases, their wireless communication module is not capable of receiving messages. The tracking devices and the mobile telephone constitute a small system for not losing objects. The mobile telephones do not constitute a community. Even though they can communicate with each other via the mobile telephone communication network, they cannot, for lack of a suitable application program, communicate with the short-range wireless communication modules of the other mobile phones are the very wireless communication modules that can receive tracking messages. If the mobile telephone rather than the tracking device raises the alarm, it might inquire from the object owner as to whether the object is lost, depending on the specific purpose of the alarm.
U.S. Pat. No. 7,098,786 describes such a tracking device that can receive messages. Upon instruction by the mobile telephone, it can increase or decrease the mean power over time of the wireless communication module by increasing, or respectively decreasing the mean sending power over the course of a tracking message. Thus, the approximate distance between object and mobile telephone at which an alarm is triggered is being adapted to the circumstances.
A loss-prevention tracking device according to the pre-characterizing parts of claim 1 and claim 10 is known from U.S. Pat. No. 7,664,463. It switches on its wireless communication module in consequence of a signal from its motion detector, or after a predetermined period. The wireless communication module then sends messages according to the Bluetooth standard and observes whether it obtains an answer with an identification of a data processing device that is allocated to it. Failing such an answer, it attempts at once to focus attention on itself by raising an alert, for instance by means of a loudspeaker. If it does obtain this answer, it switches the wireless communication module off again so as to preserve its electrical power source.
One can integrate a tracking device into a system for finding objects. U.S. Pat. No. 2010/00,164,715 discloses such systems, as well as a tracking device version that includes an acceleration sensor and that can post a burglary notice to a data processing device of the object owner. The tracking devices of the localization systems described therein can be reached using short-range radio technology thanks to a community of associated mobile telephones or the like, and, optionally, additionally associated stationary wireless communication installations. One of them, for instance, can notify the system computer that a tracking device has left its proximity or that it has arrived therein, optionally adding a statement on its position as found by trilateration. The system computer can present the owner with a loss inquiry by making his associated mobile telephone raise an alarm or instead with an end-of-loss notice, and optionally with a position statement, too. The power of sending and receiving short-range radio messages by the tracking devices is pre-set in accordance with the required proximity range. No tracking device adapts its wireless communication module power or other power to the circumstances in operation, in particular to whether a loss is to be assumed. Accordingly, the system computer does not post a no-loss notice to the tracking devices, nor anything else.
Finding objects necessitates communicating wirelessly with the tracking devices often. A thief might discover and remove or disable the tracking device quickly, necessitating a quick alarm response. At the typical sending rates, even short-range communication according to an energy-saving protocol quickly exhausts batteries that are customary in trade, as well as the capacity of the radio channels in the case of an aggregation of system participants.
The object of the present invention is overcoming such problems.